Backyard Aquaponics
A place to discuss aquaponics

cool. it seems all so long ago.......................LOL

Okay - time for some experiments to fix this PH issue. Bloody PH was back to 6 again tonight. KH is 0-1dKH and GH is 13dGH.

I have now added 78gms of CACO3. Will test again tomorrow to see what affect it has had. Am hoping for an increase of about 2dKH. Not sure what the PH effect will be. All up - as stated above I will probably want to add at least 5 times what I did tonight. Just taking it easy though.

VB what are you using as a test kit? I know with pool water test kits the reagents need to be refridgerated or they go off and give a false reading. I assume it is the same for aquarium test kits? Could be wrong though!!

Aussie

Aussie

Nothing on the packs indicating that and tests seem to be saying the right thing. Fact is my tank water has bugger all KH, meaning it is not bufferred against PH swings. This is why my PH was 6.4 last night and 6.0 tonight. The nitrification process is pulling the PH down far too easily which in is effecting the vigour of the bacteria. WHen you gonna start your thread Aussie. Am keen to hear more about your proposed greenhouse.

Have added the pics of the fish tank standpipe system to page 30 now.

On the ph issue. I have been adding shell grit over the past months at the rate of a couple of kilos at a time, and the ph has gradually drifted over a month or so, at which time I add another couple of kilos. Since the last addition, the ph hasn't really changed ie it is sitting at around 7.2 and has been for weeks, even with top ups of rain water which is 6.5 and pretty heavy feeding.

Stu - I will put the 5kg of shell grit I bought the other day into the system on the weekend. The reason for adding the CACO3 is that I want to get a rapid improvement at this point cos the PH swings are stopping me from feeding as much as I would like. Perch are hungry as tonight - but haven't fed them anything because the nitrite is about .5, which is an indication that the nitrobacter have slowed.

Yep, got ya. And the quickest way to get the nitrites down is to stop feeding. Just as an aside, I have found that adding shell grit, so long as it is in the flow of water, adjusts the ph within 24 hours

Maybe I just haven't added enough in the past then. Do you add it to the grow-beds or have it in a different container. I am thinking of containing it in something and putting it in my sump where the siphon water flows in.

I have it in the growbeds, dug a hole in a non planted spot so it gets plenty of cvontact. Also I have strips of it under the irigation grids, and a layer in the biofilter above the vat, also when i did the new growbeds, I put a sausage like strip/layer on top of the perlite, so everytime it floods, it gets contacted.

VB, i know its late and i'm tired, but ive read your post 3 times and i'm still confused.

CaCO3 is calcium carbonate AKA shell grit AKA seashells AKA crushed coral. If it IS CACO3 then your adding shellgrit in effect and won't get any rapid changes at all.

Are you SURE you don't mean calcium hydroxide?

Dude, just use the standard bi-carb to bring it up say 0.5 PH per day and add your KG's of shell grit.

The bicarb will give you instant results and the Kg's of shell grit will keep it there.

Don't fret about the amount of bi-carb you use if its a once off thing, don't forget the volume of water you're dosing is big. if the plants survived a salt dosing then they'll survive the bi-carb (and you'll be using much less)

Thats what i'd do, anyway.

Steve

The calcium carbonate I am using is a fine white powder. I believe that chalk is calcium carbonate. I expect that the change would be more rapid than using shell grit because of the form of the calcium carbonate - ie fine poder that should disolve more easilly in the water. Will wait and see I guess. I have been adding bi-carb and the ph has rissen but has stayed there for hardly any time at all.

I see what you're sating about te fine powder, but the problem is that calcium carbonate is very INSOLUBLE. You'll find that if you mix up even a teaspoon in a glass of water it will settle at the bottom on standing for a while.

Suck it and see, i guess.

With the bi-carb: From memory i used to use about a table spoon per 200lt in my tropical aquarium to raise it from low 6's to 7.0.............so i reckon you'd be looking at almost a small packet or so for a few thousand litres.

My system only holds about 1300 litres. I have been putting decent quantities in to raise the ph by .4 or .5 points over a couple of days. The nitrification is making it drop quite rapidly. I suspect that part of the PH drop is related to the amount of solids now in my grow-bed. Hopefully the CaCO3 in powder and shell grit form will buffer my system and stop this from happening. I would hate to have to clean out the gravel. The ecosystem I have created in there has to be good. At night time I can see worms sticking their heads out of the gravel - particularly where the water is flowing onto the gravel bed. It's pretty cool.

BTW - the powder CaCO3 was cheaper than the shell grit at only $1.15 a kilo. THe shell grit is pretty crap - full of impurities like sand and dirt.

go the powder over the grit then, cheaper is better in this case it will settle nicely in your GB.

You got me worried now, might check my system ph tomorrow, but i'm not feeding much and i only have 7 odd fish in there atm.

a few Kg's should see you though for quite a while............